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Small Wonders: Ursa Major

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Object

Type

Size

Mag

RA

Dec

Target

NGC 2841

Galaxy

8.1'x3.5'

9.3

09h 22m 30.0s

+50° 57' 09"

NGC 2976

Galaxy

5.9'x2.7'

10.1

09h 47m 49.0s

+67° 53' 30"

M 81

Galaxy

24.9'x11.5'

7

09h 56m 08.2s

+69° 02' 26"

M 82

Galaxy

11.2'x4.3'

8.6

09h 56m 29.1s

+69° 39' 23"

NGC 3077

Galaxy

5.2'x4.7'

10

10h 03m 54.2s

+68° 42' 27"

IC 2574

Galaxy

13.2'x5.4'

10.2

10h 28m 54.2s

+68° 23' 13"

M 108

Galaxy

8.6'x2.4'

9.9

11h 11m 54.1s

+55° 38' 21"

M 97

Planetary Nebula

2.8'

9.9

11h 15m 12.1s

+54° 59' 08"

NGC 3718

Galaxy

8.1'x4.0'

10.6

11h 32m 57.9s

+53° 01' 56"

NGC 3729

Galaxy

2.9'x1.9'

11

11h 34m 12.4s

+53° 05' 29"

NGC 3953

Galaxy

6.9'x3.6'

9.8

11h 54m 10.6s

+52° 17' 21"

M 109

Galaxy

7.5'x4.4'

9.8

11h 57m 57.5s

+53° 20' 16"

Cr 285

Open Cluster

1400.0'

0.4

12h 03m 22.2s

+57° 57' 51"

M 101

Galaxy

28.8'x26.9'

7.5

14h 03m 28.1s

+54° 18' 54"

NGC 5474

Galaxy

4.7'x4.7'

10.6

14h 05m 17.1s

+53° 37' 42"

Challenge

HCG56

Galaxy Cluster

14.5

11h 33m 11.2s

+52° 51' 54"

HCG41

Galaxy Cluster

13.9

09h 58m 07.4s

+45° 10' 19"

Our
constellation for this edition of Small Wonders is familiar to any
denizen of the northern hemisphere. Throughout history,
Ursa Major
has been a recongnizable figure in the night sky. It’s alternately been
seen as a bear, three hunters and a bear, a plough, a bear and a wagon. (Did I mention that it's been seen as a bear?)
The
asterism it contains – the Big Dipper – is probably the most commonly
recognized figure in the night sky. The Dipper serves as a guide
post
to many of the northern hemisphere constellations, and is itself an
open cluster. Designated Collinder 285, or the Ursa Major Moving
Group, it contains the five central stars of the Dipper and is centered
a mere 70 light years from earth. Cr285 best viewed with the
naked
eye.

Many of the targets this month are visible in binoculars.

The Dipper is a cornucopia of deep sky delights. Lying well off
the
Milky Way and covering over 1280 degrees of sky, this is a very large
patch of space looking far out into intergalactic reaches. Ursa
Major
is therefore, unsurprisingly, rich in galaxies and galactic
clusters.
But it’s home to a number of other interesting targets as well: thousands of galaxies brighter than mag 20 (on a more realistic limit, there
are 812 at mag 15 or brighter, and 56 brighter than mag 12), 7
Hickson
groups, 327 Abell Galaxy Clusters, 641 quasars (MKN 421 @ 11h05, +38
deg 11 min and mag 13.5 is the brightest), two planetary nebula, 9
diffuse nebula, and one globular cluster (Palomar 4) – to list a
few.

There are several stars of note in Ursa Major – outside of the stars of
the dipper, UMa also contains Lalande 21185 – a mag 7.49 red dwarf –
which is the 4th closest star to the solar system and located a mere
8.1 light years away. Lalande 21185 is the brightest red dwarf
visible
from the northern hemisphere. UMa is also home to Groombridge
1830 –
at mag 6.45, it lies 28 light years away and has the third fastest
proper motion of any other known stars. Groombridge 1830 is
a
population II object and as old as the galaxy’s globulars.
Another
star of note in Ursa Major is 47 Ursae Majoris - which is one of the
(many) extrasolar systems to have a (suspected) planetary inhabitant.

Ursa Major houses a total of 7 Messier Objects – 6 that are of interest
visually. (We’ll toss out M40, although double star observers
might
want to take a gander at it.)

The Great Bear is also home to the first Hubble Deep Field at 12h 36m
49.4000s +62d 12' 58.000", this tiny window (about the
size of a grain of rice held at arms length) let the HST look outside our galaxy
and capture at least 1500 galaxies in a 10 day long exposure.
Nearly everything you can see in the image below is a galaxy. (If
you
have a high bandwidth connection, be sure to see "Zooming In to the
Hubble deep field" in the links at the end of this article.)

Star names in the Dipper

Before we go further, lets be on a first name basis with the stars that make up the Dipper proper.
Starting at the handle, we have Alkaid, then the naked eye double Alcor
and Mizar is found at the handles bend. Moving on down the ladle
we
come to Alioth, and a little further leads us to the first of the stars
that mark the bowl of the Dipper – Megrez. Down the first side we
hit
Phecda, then Merak and Dubhe. One of the first things any novice
learns is to line up Merak and Dubhe and use them as pointers to find
Polaris, the North Star in Ursa Minor.

Various sources I’ve
read have said that many civilizations and
cultures used Alcor and Mizar as tests of visual
acuity, but this has often puzzled me a bit, as I’ve never found them
all that difficult to separate.

Frankly, Ursa Major is a daunting consellation to write a sky tour for: it’s absolutely massive, and home to dozens of targets for an
observer with even the most modest of telescopes. Because of this,
I’ve
concentrated on what I consider to be the brightest and most
spectacular objects, but one area I’ve neglected is what Walter Scott
Houston called “The Bowl Of Night” – the bowl of the Big Dipper
itself. Once you’ve finished this month’s tour, I’d encourage you
to
spend some time scanning in the bowl itself – you’ll find several
targets worthy of a moderate telescope, and I provide a map and listing
of some of the brighter galaxies in and around the bowl at the end of
this article.

Bottom of the Bowl Finder
Chart

We’ll start off tonights tour at the bottom of the bowl on a line
connecting Phecda and Merak. Just to the south east of
Phecda, (the
star at the bottom of the bowl closest to the handle), we’ll find our
first Messier target for the evening: M109.

Discovered by Merchain, M109 was known by Messier but didn’t appear on
“his” list until the middle of the 20th century. Messiers
original
list consisted of 103 targets with some of them questionable (M40 – a
double star, and the “missing” messier – M102).

M109 Image courtesy Jason
Blaschka

Jason Blaschka’s photo of M109 is astounding, but bears little
resemblance to what I see even in the largest telescopes. Some of
the
features are there – the galaxy bears a marked resemblance to a tie
fighter even in my 4” apos – under good skies - the central bar is
often visible, but it's a rare night on which I catch hints of the spiral arms in small apertures.

M109
Sketch Courtesy Jay Michaels

Jay Michaels excellent drawing is a good example of what can be seen in
an 8-10 inch scope on a good night.

While you are in the area, take a moment to look for NGC 3953 about a
degree south of M109.

Afterwards move up towards the middle of the bottom then drop a bit south to find a nice cluster of
objects – NGC3718, NGC 3729 and one of our challenge objects for the
month – Hickson 56.

Visually you’ll
find both 3718 and 3729 lie within the same moderate
power field of view – I find 3718 to be about three times larger than
3729, but to my eye both galaxies are fairly similar. In larger
telescopes, I find that both have visible (if faint) cores, and a
dispersed outer halo. Just a bit to the south, you’ll find
Hickson 56
– but we’ll come back to that one in a bit.

Move back up towards the bottom pointer star (Merak) with a low power
wide field eyepiece, and you’ll run across a celestial odd
couple.
First into view should be M97 – the Owl Nebula. A planetary nebula discovered by
Merchain
in 1781, I’ve found that this is one of those few objects which
actually resembles it’s nickname. Even in small scopes (under
good
conditions) I can catch a glimpse of the dark spots which form the owls
eyes. It’s fairly large, and as such the surface brightness is
quite
low. Some observers have claimed to see blue or green across the
face
of the disk – on excellent nights, I’ve caught hints of green in large
telescopes, but it usually appears simply grey.

Image Courtesy Rick Krejecki

Rick Krejecki’s shot of M97 is amazing. Take a gander at
the full
resolution version on his web site
(http://www.ricksastro.com/DSOs/owl_XT_xscope.shtml)
– you can spend a
fair amount of time just counting the tiny background galaxies. I
wonder if any of these have been spotted visually by observers with
giant telescopes?

If we want to look at extragalactic targets we don’t have to
look far away – just a little closer to Merak you’ll find the edge on barred
spiral M108. Spend some time experimenting with
different
magnifications on this target – see what, if any mottling you can make
out, and if you can detect any presence of an outer halo.

M108
and M97 Image Courtesy Tom Nicolades

Tom Nicolades excellent shot shows a bruised and battered M108 and an
electric blue M97 in the same frame, and in low power wide field views
(anything providing more than 1 degree TFOV), both can easily be caught
in the same field of view.

NGC
2841 Area

While we’re here,
let’s hop down the front legs of the bowl and take a
quick gander at 2841. This mag 9.2 galaxy will present a nice sliver
of
light for moderately sized telescopes. A bright core region is
surrounded by a slightly dimmer halo. If you have a larger
telescope,
look for a dust lane marked by a sharp fading of the halo on one side
of the galaxy.

M81
/ M82 Image Courtesy John Moody

When you’ve finished with 2841, let’s move on to two of the real
showpieces in the Great Bear; M81 and M82.

M81 / M82 Area

M81 and 82 are a spectacular pairing of galaxies visible even through
small
binoculars. Separated by a mere 3/4 degree both are
visible in wide field telescopes and present a wonderful pairing.
Discovered by Bode in 1774, they are examples of galactic morphology
which couldn’t appear to be more different from one another other. Both are
members of a small cluster of galaxies called the M81 group (which lies
a neighborly 10 million light years away), so I suppose it would be
appropriate to discuss M81 first. In smaller telescopes, M81 is a
bright oval, but large scopes begin to show it’s spiral
structure. M81
is by far the larger and brighter of the two, and in long exposure
photographs is a classic spiral. M82, by contrast, is a tortured
irregular that looks like it’s been the
looser in some vast celestial conflict. In my 18”, I see it bent at one end while the mottling
is
clearly apparent, along with a nearly clean division around 1/3 of the
way from one edge. While it’s slightly fainter than M81, visually
I
find it far more impressive.

It’s worth noting that this is one of the few DSO’s visual observers
have reported color in, but don’t grab those 80mm scopes in anticipation
yet. While a friend of mine in Arizona with access to a 30 inch
telescope describes seeing red or pink, I’ve yet to see it even tho
I’ve gazed at this object with telescopes up to 25” in size. I
suspect
it takes an excellent night, good optics, and as much aperture as you
can throw at it.

Don’t despair however – in my opinion, M82 is one of the finest
targets in the night sky – color or not. Even in small scopes,
these
two are stunning, and can be picked out from dark skies with the slightest optical aid.

Image Courtesy Carol Lakomiak

Carol Lakomiak’s sketch of the area provides an excellent example of
what can been seen in large binoculars or a small telescope.

As you’ll note in the area chart, there are a number of other targets
in this region as well – take the time to scout around a little bit -
keep an eye out for NGC 3077, 2976 and IC 2574. In large
scopes, I
find that NGC 3077 and 2976 bear a resemblance to glimpses I’ve had of
M81 in smaller apertures. When I’m star hopping and stumble on one of these
one
first, it can get quite confusing trying to find M81. Always keep
your
expectations in line with your aperture.

We haven’t even really begun to cover the possibilities in Ursa Major,
but we’ll make one more basic pit stop for the night and then introduce
two challenge objects.

M101 Area

Head over around the top of the dipper and back the handle for M101 –
the Pinwheel Galaxy. Discovered by Mechain in 1781, it’s truly a
spectacular object in a large telescope showing obvious spiral
structure and mottling across the arms.

M101 is a large, loose face on object that can be decptively difficult in
small telescopes. Keep in mind when searching you are looking for
a
large object - around 2/3 the size of the full moon, but the surface
brightness is very faint so keep your eyes peeled for a gradual
lightning of the sky background.

The galaxy is huge – sources put it from 170,000 to 190,000
light years across, some 25 million light years away and home to some
of the most spectacular and immense star forming areas known.

Many of these giant starbirth areas are bright enough to merit their own
NGC
numbers - NGC 5441, 5447, 5450, 5449, 5451, 5453, 5458, 5461, 5462, and
5471. 5471 is the largest and brightest HII region in M101 –
far
larger than anything comparable in the Milky Way (and has been proposed
to contain a hypernova in 5471B). These are visible in larger
telescopes, and while often I’d recommend a power to view the galaxy at (my
favorite galaxy buster is my 13t6 nagler in my 18” Obsession, it
provides a magnification of around 180x, and a nice wide field), because of its detailed structure, I’d rather recommend
that you spend a while examining it at high and low
powers to find what works best for you. Be sure
to take a gander for some of the brighter HII regions. Note that
5450
and 5447 are overlapped in the image below - 5447 is the region
directly to the south of 5450.

HII Regions in M101

Like M81, M101 is the dominant member of it’s own cluster of galaxies,
so while you are in the area keep an eye out for other
interlopers.
Brighter neighbors include NGC 5474 and NGC 5473 but numerous other
galaxies reside in the area.

M101 image courtesy James
Jacobson

Challenge Objects

There are several objects worthy of the challenge tag in Ursa Major – 6
Hickson groups, Palomar 4 (a globular cluster), and a fairly bright
quasar
were the first that came to mind. Quasars are interesting for
what
they are – not what you see, and Palomar 4 is certainly doable with a large scope
from a dark site, but on the whole I tend to prefer galaxy
groupings.
With that in mind, I present as challenge objects two of the
“brightest” Hickson’s in Ursa Major – Hickson 56 and Hickson 41.

Hickson 56 Finder Chart

Hickson 56 lies just to the south of a galaxy pair we visited earlier –
NGC 3729 and 3718.

Hickson 56 finder chart

Note that the position of Hickson 56 is slightly off in the image
above.

Hickson 56 has 5 components (although not all may be visible) that
range from magnitude 16.2 to 15.8, and all the components are tiny (the
largest is 1.3x.2 arc seconds) – so make sure you try for this one
under good skies with plenty of aperture.

Iiro Sairanen from Härskiänsaari, Ruokolahti, Finland
observed Hickson
56 with his 16 inch Newtonian at 292x and provided the following
sketch:

Sketch of Hickson 56 Courtesy
Iiro Sairanen.

The other challenge object this month is Hickson 41.

Wide field Chart

Area Finder Chart

Hickson 41 is a
little more difficult to get to, but it’s a little
brighter. Again, note that it does not perfectly match up with the charts provided. Use the DSS images for reference. There are 4 listed components ranging in magnitude from
14.6
to 18.1, with the largest being a mere 1.5x.2 arcseconds in size.
Alvin Huey, in his excellent Hickson Group Observer’s Guide observing
at 377 and 528x, was unable to catch the 4th member of the group with
his 22” f4.1 dobsonian.

I was able to catch three of the four galaxies in my 18” f4.5 from my
driveway, but it necessitated some extreme measures; I used a towel to
cover my head and shield all extraneous light, I needed a good evening (for my
driveway), and I used extremely high powers (600x) in order to
darken the sky background sufficiently. Finally, I had to resort
to
rapping the side of the telescope in order to ensure that I had spotted
all three of the members.

The Hicksons, for the most part, are not casual observation or quick
look targets. Use every trick in the book including high magnification and perserverence to glimpse these tiny groups of interacting galaxies.

Additional Targets

As I alluded above, Walter Scott Houston called this area the "Bowl of
Night - with that in mind, here's a map to some other suggestions for the Dipper's bowl.